Previously, people could carry out tests they ordered online at home and send away their results, but were diagnosed over the phone.

It is hoped the move will help the UK’s 25,000 undiagnosed HIV-positive people.

No tests have yet been developed that pass European guidelines, said the government’s health regulator.

Home testing for HIV was approved by the government last September but the law only came into effect on Sunday.

The Terrence Higgins Trust HIV charity said the tests could be introduced into the UK this year or in early 2015.

The UK is leading Europe in making the kits available over the counter, but they were introduced to the US in 2012.

Testing could involve taking a small drop of blood from a finger, or a swab from the inside of the mouth.

‘Key strut’ of HIV prevention

Dr Michael Brady, medical director at the Terrence Higgins Trust, said it was a “shame” the change in the law was coming into effect when no viable tests were available.

The charity recently ran a scheme where participants were able to test themselves at home, send the results away by post and then receive a diagnosis over the phone, or by text message, if negative.

Dr Brady said: “What we had not anticipated was just how popular the scheme would be, with demand very nearly outstripping supply on more than one occasion.”

The trust found that 97% of 915 users in its study said they would use the HIV self-sampling again. The charity said that in one weekend it received 3,000 orders for the test.

He said such feedback indicated home testing would form a “key strut” of the charity’s prevention work in the UK.

But Dr Brady added: “It [home testing] is not for everyone, which is why it is important to have a range of options available.”

He said it was important for users to access NHS facilities such as counselling and treatment if they found out at home they were HIV-positive.

‘Convenient and discreet’

A spokesperson for the Department for Health said: “The stigma surrounding HIV may mean that some people are afraid or reluctant to go to a clinic to be tested.

“The change in the law will mean self-test kits are now legal to buy, making the test process more convenient and discreet.”

She said although no kits meeting European standards were available in the UK, the government “expected this to change” in the next year.

“HIV testing remains free on the NHS – anybody with concerns can visit their GUM Clinic, GP or contact the Terrence Higgins Trust’s confidential helpline. Self-sampling kits are also available to buy,” she added.

Online tests ‘unreliable’

Heather Leake Date, HIV specialist pharmacist and spokesperson for the Royal Pharmaceutical Society, said the tests would help reduce the risk of new HIV infections.

She said: “HIV self-testing kits may help increase diagnosis by providing more choice for people who have been at risk but are reluctant to get a test in person from existing services.”

Ms Leake Date said kits currently available online could be unreliable and give “false results”.

She added: “When kits become available, people should buy from a trusted source and check for the CE mark, which means it will have been assessed for quality and safety.”

But while they have lived longer than expected, their lives have not been straightforward.

Many suffer chronic health complications, including disfigurement, and as a result are socially ostracised.

Dr Ferrand now treats these teenagers in Zimbabwe and is a passionate advocate for them.

“These children are more likely to be poor and to have lost their parents to Aids,” she said. “They’ve been shifted around amongst guardians and missed education, so the odds are stacked against them.”

‘Untreated HIV infection’

Sub-Saharan Africa accounts for 69% of the world’s HIV cases. Today, nearly one in 20 adults live with the condition.

Life-saving antiretroviral therapy (ART) has been available for free since 2004 in the region and has transformed the outlook of those with the virus.

But children like Tadisa who survived unexpectedly have often gone untreated, and the complications of untreated HIV – such as damage to the lungs and heart – are debilitating.

“There’s also some brain damage leading to them not being able to perform in school,” said Dr Ferrand. “There are some obvious visible signs of longstanding untreated HIV infection, such as stunting and skin disfigurement.

Part of the problem is a lack of awareness: four out of five children with HIV do not know that they have the virus.

Their medical problems are often put down to normal childhood illnesses and they do not get tested for HIV until they are in their teens.

‘Culture of silence’

Dr Ferrand described a “culture of silence” and said the “most shocking” aspect of her research was that nearly all the older children and adolescents who have tested positive could have been diagnosed earlier.

Two-thirds had been to a primary health care clinic in the previous six months, a quarter had been in hospital at some point in their lives, and more than half had a parent or sibling with HIV.

Despite this, no-one had thought to test them for HIV.

Once tested, there was no standard way for young people to be told of their status, according to research at Harare’s Parirenyatwa Ol Clinic by Dr Ferrand and her colleagues.

They asked 31 patients aged between 16 and 20 how they discovered they were HIV-positive.

Although the advice was for their parents or guardians to tell them, the adolescents preferred to hear the news for themselves.

“I wanted to be told at the clinic just so I know that it’s really true, that I’ve been tested, and it’s true”, said one 17 year-old girl.

Some children had guessed, such as one 17-year-old boy who told the researchers: “My mother was lying to me saying I have a heart problem, I have a hole in my heart. So I decided to say, ‘Okay.’

“But I knew. I knew that when I was coming here I was HIV-positive.”

And sometimes the news was given in an abrupt manner.

“My grandmother told me at home,” said one 18-year-old boy. “I was watching TV. My grandmother came up to me and said: ‘Hey, A, do you know that you’re HIV-positive?’ I said, ‘Okay.’ She said it twice: ‘You’re HIV-positive.’ I just said, ‘Okay.'”

Stigma

The adolescents learn most about their condition from each other rather than their parents and guardians, the researchers found.

Once diagnosed, they can keep the virus at bay with the free ARTs.

But one reason their guardians did not bring them for diagnosis and treatment was to protect them and their families.

“They fear that if the child is disclosed to, he will go about in the streets or at school telling others and other relatives that don’t know that the parents are positive,” said a counsellor at Parirenyatwa Ol Clinic. “So they will be stigmatized or discriminated against as a family.”

In 2013 a UNICEF report stated that only about a third of children with HIV were receiving ARTs, compared with around two-thirds of adults.

New WHO guidelines say testing should be offered to all adolescents living in areas of the world where HIV is common, particularly sub-Saharan Africa.

Dr Ferrand believes it is an issue of child rights that the young people learn about their HIV status and receive treatment.